(a) Field of the Invention
The present invention relates to a light assembly having a bulb holder is replaceably mountable in a housing with which a reflector is formed integrally.
(b) Description of the Prior Art
Generally, the automotive light assembly comprises a housing with which a reflector having a reflective surface like a paraboloid of revolution is formed integrally, a bulb holder mountable from outside through an opening provided near the apex of the reflective surface in such a manner that the bulb filament is positioned near the focal point of the reflective surface of the reflector, and a lens provided at the front of the housing These elements are so arranged that the light emitted from the filament in the bulb is projected as reflected by the reflective surface of the reflector and refracted through the lens to provide a predetermined pattern of light distribution ahead of an automobile on which the light assembly is mounted.
Even in case cars used in the USA and Europe are of a same model, the distribution pattern of light reflected ahead by the reflector of a light assembly provided on the cars is subject to one standard in the USA and to other in the Europe. That is to say, the bulb and its associated holder of automotive light assembly are to be designed and manufactured so as to meet the requirements different in the USA from in the Europe, and also the standard applicable, in the USA, to the shape of the socket of the lamp housing including the reflector in which the bulb holder is fitted is different from that in the Europe. All the applicable standards prescribe, concerning the dimensions of the lamp units of automotive light assemblies, that the filament in the bulb of any automotive light assembly should be disposed near the focal spot of the reflective surface of the reflector. Among others, the standard in the northern American countries, especially, the Federal Motor Vehicle Safety Standards (FMVSS) in the USA and the EC Standard in the Europe stipulate in detail the dimensional requirements for the lamp units of automotive light assemblies. For example, FMVSS No. 108 prescribes a lamp unit provided with a bulb classified as #9004 and in which the filament in the bulb is about 33.5 mm distant from the position where the bulb holder is set and the outside diameter of the holder inserted in the opening in the reflector is about 33.8 mm. Also, the EP Standard defines a lamp unit provided with a bulb classified as H4 and in which the distance between the bulb filament and the position where the bulb holder is set is about 26 mm and the holder inserted in the opening in the reflector is about 34.5 mm in outside diameter In case cars exported to the USA and Europe are a same model, the spaces for the light assemblies of the cars are identical, and so the housings of the light assemblies are nearly identical in outside dimensions. However, to meet the requirements in the USA and those in the Europe, respectively, one die is used to mold the lamp housings for the light assemblies employed on the cars for the USA while other die is used to mold the lamp housings for the light assemblies on the cars for the Europe. Normally, a portion, including the reflective surface of the reflector, of the lamp housing of a light assembly used in the USA is molded using a male die A1, while a socket portion, including the opening in which the bulb holder is inserted, is molded using the female die B1. A portion, including the reflective surface of the reflector, of the lamp housing of a light assembly used in the Europe is molded using a male die A2, while a socket portion, including the opening in which the bulb holder is fitted, is molded using a female die B2. Practically, however, it is not economically advantageous to use different dies for molding lamp housings of light assemblies to be provided on cars of a same model but which are to be used in different countries. Also, since the opening of the socket portion in which the bulb holder is to be inserted is formed in the curve surface near the apex of the reflective surface of the reflector during the molding of a lamp housing, it is difficult to control the die-molding parameters which have an influence on the precision of the curved surface formed near the apex of the reflective surface.